<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      * {
        margin: 0;
        padding: 0;
      }
      body {
        display: flex;
      }
      .con {
        width: 800px;
        display: flex;
        height: 40px;
      }
      .con div {
        width: 200px;
      }
    </style>
  </head>
  <body>
    <div class="con">
      <div style="background-color: #ccc"></div>
      <div style="width: 250px; flex-grow: 2; background-color: #333"></div>
      <div style="flex-grow: 1; background-color: #666"></div>
    </div>
  </body>
  <script></script>
</html>
